State one method by which : 1. Oxygen is added to air 2. Carbon dioxide is added to air

Question

State one method by which :

1. Oxygen is added to air

2. Carbon dioxide is added to air

3. Oxygen is removed from the air

4. Carbon dioxide is removed from the air

Answer 1

1. Photosynthesis by green plants

2. Combustion of various compounds

3. Respiration by living organisms

4. Plants- during photosynthesis.